Prilokain

Prilokain, also spelled prilocaine in many languages, is an amide-type local anesthetic used to numb tissue for medical procedures. It is closely related to lidocaine and is commonly formulated for infiltration and nerve-block anesthesia, and is also found in topical preparations. A well-known topical combination is the eutectic mixture of lidocaine and prilocaine (EMLA), which provides dermal anesthesia.

The mechanism of action involves blockade of voltage-gated sodium channels in nerve membranes, which inhibits action potential generation and nerve impulse conduction. By reducing neural excitability, prilocaine prevents transmission of pain signals from the site of administration. Onset and duration depend on the route of administration, dose, and presence of vasoconstrictors; topical and infiltrative uses typically have rapid onset, and durations range from about one to several hours, extended when epinephrine or other vasoconstrictors are used.

Common clinical uses include infiltration anesthesia and regional nerve blocks in dentistry, minor dermatologic and surgical procedures, and topical anesthesia for ready-to-puncture procedures in pediatric patients (as part of EMLA). Formulations vary by region, but prilocaine is often combined with lidocaine in dental cartridges and topical products to tailor onset and duration.

Safety and metabolism: prilocaine is metabolized in the liver by amidases to o-toluidine, a metabolite associated with methemoglobinemia in some patients at higher doses. Risks are higher in infants, individuals with certain enzyme deficiencies, or with large cumulative doses. Signs of methemoglobinemia include hypoxia and cyanosis; treatment may require methylene blue. As with other local anesthetics, systemic toxicity can occur with excessive absorption or rapid administration.

See also: lidocaine, benzocaine, topical anesthetics.